Global efforts exist to develop environmentally sustainable technologies for organic waste recovery.
In modern society, waste treatment systems have played an important role in reducing diseases caused by contamination of the water supply by pathogens. The introduction of toilets made possible the transportation of organic waste directly to septic systems or a municipal treatment system. Both septic and municipal treatment systems use large amounts of municipal water resources. It is widely accepted that waste treatment systems often discharge overflows of raw sewage into downstream waterways. In the past 40 years, improvements have been made to waste treatment systems by incorporating thermophilic aerobic digestion (TAD) treatment processes which makes organic waste recovery possible.
Technology exists for treatment of biosolids. Technology also exists for dry closets, which are often referred to as dry toilets. Dry closets, which normally are not connected to water supply or sewer drains, are used globally and they do have some useful features. However, dry closets do not attain the same standards the EPA requires for Class A biosolids. A lower set of standards has been set for the dry closet industry when compared to what exists for a domestic sewage treatment facility.
A set of standards exist for domestic sewage treatment technology, and are applicable to the recovery of organic waste. The U.S. EPA defines sewage sludge as “a solid, semi-solid, or liquid residue generated during the treatment of domestic sewage in a treatment works” (EPA/832-R-93-003. September 1994, p. 4). The EPA defines biosolids as “sewage sludge that has been treated and meets state and federal standards for land application” (EPA/625/R-92/013. Revised July 2003, p. 13). Thus biosolids, as defined by the phrase “for land application”, are a form of recovered organic waste. When organic waste is mixed with water the unstable waste volume increases. One stage of sewage sludge treatment is a dewatering process. This volume reduction process must take place. before further treatments can occur.
Standards for Class A biosolids are discussed in EPA publication EPA/625/R-92/013 (Revised July 2003).
a. According to the EPA, “Sewage sludge is considered to be Class A if it has been treated in one of the Processes to Further Reduce Pathogens (PFRPs)” (EPA/625/R-92/013. Revised July 2003, p. 32). Composting, TAD and pasteurization are listed as processes for PFRP, each having different procedures required to achieve Class A pathogen reduction.
b. “Thermophilic aerobic digestion is a refinement of the conventional aerobic digestion processes. Because there is less sewage sludge volume and less air to carry away heat, the heat released from biological oxidation warms the sewage sludge in the digester to as high as 60° C. (140° F.). Because of the increased temperatures, this process achieves higher rates of organic solids reduction than are achieved by conventional aerobic digestion which operates at ambient air temperature. The biodegradable volatile solids content of the sewage sludge can be reduced by up to 70% in a relatively short time. The digested sewage sludge is effectively pasteurized due to the high temperatures” (EPA/625/R-92/013. Revised July 2003, p. 54). Pathogenic organisms are reduced to below detectable limits if the process is carried out at temperatures above 55° C. (131° F.).
c. “Vectors are any living organism capable of transmitting a pathogen from one organism to another either mechanically (by simply transporting the pathogen) or biologically by playing a specific role in the life cycle of the pathogen. Vectors for sewage sludge pathogens include insects, rodents and birds.” Furthermore, “The term ‘stability’ is often used to describe sewage sludge. Although it is associated with vector attraction reduction, stability is not regulated by the Part 503 Rule. With regard to sewage sludge, stability is generally defined as the point at which food for rapid microbial activity is no longer available.” (EPA/625/R-92/013. Revised July 2003, p. 58). In order to achieve reduced vector attraction, “The sewage sludge must be aerobically treated for 14 days or longer during which time the temperature must be over 40° C. (104° F.) and the average temperature higher than 45° C. (113° F.).” (EPA/625/R-92/013. Revised July 2003, p. 61).
d. “EQ biosolids are biosolids which have met the Part 503 pollutant concentration limits.” (EPA/625/R-92/013. Revised July 2003, p. 20). EQ biosolids must also meet Class A requirements. U.S. EPA regulations require that all biosolids applied to the land must meet the ceiling concentrations for pollutants. The ceiling concentrations are the maximum concentration limits for 10 heavy metal pollutants in biosolids, “specifically, arsenic, cadmium, chromium, copper, lead, mercury, molybdenum, nickel, selenium, and zinc.” (EPA/832-R-93-003. September 1994, p. 30). Once the requirements are met, “EQ biosolids are considered a product that is virtually unregulated for use, whether used in bulk, or sold or given away in bags or other containers.” (EPA/832-R-93-003. September 1994, p. 7).
There is a large difference between domestic sewage treatment technology and dry closet technology. This is reflected in the standards set by the U.S. EPA for composting toilets requiring that “All waste materials should be disposed of in accordance with the state and local regulations.” (EPA 832-F-99-066. September 1999. p. 6). There is no allowance for land application or organic waste recovery set forth within the EPA standard for composting toilets. Dry closets of the composting toilet type are generally intended to provide an alternative to a septic system or the need for a municipal treatment system. However, all waste material generated from composting toilets must be disposed of in accordance with state and local regulations. This presents a need for further treatment to achieve organic waste recovery when using a dry closet of the composting toilet type. There is a need to develop new processes and technologies for a new type of dry closet which meet the standards set by the U.S. EPA for the treatment of domestic sewage.
Most dry closets of the composting toilet type do not add water to organic waste or form a mixture of sewage sludge. When water is not added to organic waste, the dewatering process is not needed. This allows the preferred method of use to be dry aerobic digestion. Furthermore, since dry closets don't introduce heavy metal pollutants into the waste treatment process, it becomes possible to produce an aggregate result that meets requirements for EQ biosolids.
Technologies used in dry closets of the composting toilet type have some limitations. These dry closets rely on a thermophilic aerobic bacterial environment. U.S. Pat. No. 3,959,829 (PETER NORDGREN Jun. 4, 1976) describes a dry closet which uses an exhaust fan for ventilation and has “independently controllable heating means” which are used to bring the “said chamber to pasteurizing temperature”. U.S. Pat. No. 4,343,051 (NILS C.PERSSON Aug. 10, 1982) describes a decomposition container with “the attainment of a rapid thermophilic decomposition process” and “a stirrer rotatable by means of an electric motor”. U.S. Pat. No. 5,303,431 (LASSE JOHANSSON Apr. 19, 1994) incorporates “construction in which the outer drum is thermally insulated” within a composting toilet. Dry closet technology is limited by the need for ventilation. Ventilation is counterproductive to heat efficiency needed for thermophilic and pasteurization processes that rely on retained heat that is normally ventilated.
Urine introduced to an aerobic bacterial environment produces ammonia and causes intolerable odor conditions. Most composting toilets use continuous fan ventilation to prevent the accumulation of ammonia. Although ventilation removes waste gases and odors, it also removes heat needed for an efficient thermophilic environment. When no gas recovery process is employed, the waste gases are vented into the atmosphere. Some dry toilets divert the urine in an effort to address the problem of excessive ammonia gases being vented. Urine collection can require a large storage volume and become unpleasant to handle which is a challenge for some users. An example of a dry toilet that separates the urine is found in U.S. Pat. No. 420,332 (THOMAS W. CARRICO May 28, 1889) which describes a dry-earth closet having “a smaller perforated hopper, for the reception of the liquid excrements” anticipating that “the solids and liquid excrements will be perfectly separated”.
There is a need to develop a process to stabilize and recover ammonia gases which are normally lost through ventilation. It is known that Copper(II) hydroxide can be produced from an aqueous solution of copper sulphate using sodium hydroxide or ammonia. The Copper(II) hydroxide precipitate can then be dissolved in a solution of ammonia. This process is known as Schweizer's reagent. Schweizer's reagent requires a chemical preparation stage of the transition metal. A stable metal ammine complex is formed when ammonia bonds with the transition metal. Therefore, a potential exists to develop a technology to stabilize ammonia gases based on the concept of this known process.
U.S. Patent application 2004/0023363A1 (BERNARD VAN DYK Biofiltering System for Treating Air. Feb. 5, 2004) discusses an apparatus and method “for removing odor-causing substances from the air” by using microorganisms capable of digesting the odor-causing substances. Thus, a potential exists to develop a biofiltration technology that will recover organic waste gases by incorporating a biofilter within an organic waste treatment process and device.
Dry toilets of the composting type have a limitation related to an inability to degrade lignins, the complex organic polymers which bind cellulose structure. Most composting toilets create feedstock by adding a cellulose carbon source. Some composting methods use fungal activity to degrade lignin and provide further treatment of waste material produced by composting toilets. The research paper by Deangeles, et al. “Characterization of Trapped Lignin-Degrading Microbes in Tropical Forest Soil” suggests that lignin can be transformed by microorganism produced enzymes. The authors state that “Lignin is often the most difficult portion of plant biomass to degrade, with fungi generally thought to dominate during late stage decomposition”. In addition, the exploration of microbial lignin-degraders suggests “mechanisms that are different from known fungal decomposers” and “phenol oxidase and peroxidase enzyme activity was found.” (http://doi.prg/10.1371/journal.pone.0019306.2011.p 1). U.S. Pat. No. 6,184,014B (TAKASHI ECHIGO Feb. 6, 2001) discusses a method to produce polyphenol oxidases from bacteria. This process needs the “optimum reaction temperature of the enzyme to be between 60 degrees C. and 80 degrees C.”. Thus, the potential exists for lignin transformation by bacterial enzymes when certain conditions are met. There is a need to develop a new type of dry closet device that maintains an optimal environment for lignin transformation in a consistent and reliable manner.
Many dry closets require additional vent and drain infrastructure, which decreases their affordability. There is a need for a new type of dry closet device that can employ an organic waste treatment process while needing fewer infrastructural requirements.
Digestate is the material remaining after the anaerobic digestion of biowaste. The Northern Ireland Environment Agency (NIEA) has published a quality protocol to provide approved standards for digestate. In the UK, digestate is used as a nutrient-rich product. Digestate is directly related to the anaerobic process.
The term “biosynthate” is used in reference to the aerobic process. Biosynthate is used to denote the aggregate result of biosynthesis. Conceptually, “biosynthate refers to an aggregate measurement” of biosynthesis (Biotechnology and Bioengineering. 2013. P. 4). Biosynthate is useful to identify the material remaining after aerobic digestion of biowaste in an aerobic organic waste recovery process and device.
There exists a need for devices and processes that are an improvement to existing dry closet technology in order to decrease demand on domestic sewage treatment facilities. A new device is needed that employs a point-of-use organic waste treatment process for use in either dry closets or other larger scaled applications. A new technology is also needed to reduce greenhouse gas emissions of carbon dioxide and ammonia that come from organic waste treatment systems. Thus, there is a need for devices that separate, isolate and pasteurize organic waste solids, liquids and gases. There remains a considerable need for apparatus and methods that are self-contained and able to fully recover organic waste material in a manner consistent with standards set by the U.S. EPA for Class A (EQ) Biosolids.
All references used in these specifications are incorporated herein by reference in their entirety. Furthermore, where a definition or use of a term in a reference which is incorporated by reference herein is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein supersedes the definition of that term in the reference.